If they voted in favor, most Swiss would probably have to be considered morally inconsistent, because most of them will often cross the border with Italy, Germany or France just to have a nice meal at a restaurant (in Switzerland is already really expensive to the point of justifying the short trip). So in this case they would basically be saying that it's not ok to be paid less then 22 francs, but they are more than happy using a service where people earn much less than that. "But probably they will leave a huge tip for the staff in those countries". Well, I don't think so. In other words, as always, "it's easy to love 'humanity', but too damn hard to love the individual next to you", isn't it? Overall there is a lot of hypocrisy in those that support minimum wage, as a lot of them will say: "everybody should have a 'descent' wage", but then they are pretty happy buying cheap gadgets made by low paid Chinese people and using the remaining cash at their disposal for something else, maybe a nice trip for which they bought a low cost ticket, which is cheap also because the baggage handler doesn't get paid 22 francs an hour, not even that poor Ryanair stewardess earns that much money. But I'm sure many supporters of minimum wage would be outraged if their London-Lisbon return ticket cost more than £100. For more than that they would expect at least the poor stewardess to blow them.
Any top down attempt to build a "just society" makes no sense. What is "just"? Even if you can define that, given the complexity of our society, do you know what are the steps to be taken to achieve your perfect world? Are you God or something, knowing all the variables out there and how they interact? "Yes, almost. I have Big Data, AI, super computers bla bla bla, and we live in a post scarcity society bla bla bla". If it's like that I'm really sorry my Lord, you are right, my bad for ever doubting on your powers and kindness, please rule over me and my fellow humans.
Anyway, some jobs would be pushed to the black market, leaving the poorer, that you initially intended to protect, with less protection and guarantees. And what about those that are low skilled, they won't be able to gain access to the job market and to acquire the productivity and experience that could justify being paid 22 francs an hour one day.